茂钛均相催化剂丁二烯聚合研究

SYNTHESIS OF POLYBUTADIENE WITH TITANOCENE CATALYST

由五甲基单茂钛化合物Cp TiL3 和甲基铝氧烷 (MAO)组成的催化体系进行丁二烯聚合 .考察具有不同辅助配体L的主催化剂Cp TiL3 及外加三异丁基铝 (TIBA)对聚合的选择性 ;讨论了聚合温度、AlMAO Ti摩尔比和催化剂浓度对聚合反应的影响 .发现外加适量TIBA有助于提高催化活性 ,而且随着TIBA用量的增加聚丁二烯分子量增加 .结合钛氧化态分析 ,说明催化体系中Ti(Ⅲ )

Polybutadienes were synthesized with η 5\|pentamethycyclopentadienyltri group titanium \[Cp\+*TiL\-3,L=chloride,benzyloxy, p methoxyphenoxy\] in the presence of methylaluminoxane (MAO).The influences of polymerization temperature [ T \-p],catalyst concentration [Ti] and Al MAO /Ti molar ratio on butadiene polymerization have been studied.The external addition of triisobutylaluminum (TIBA) into the catalyst system gave a great promotion on the catalytic activity and the molecular weight of polybutadienes.The results showed that the best polymerization conditions with Cp\+*Ti(OBz) 3/MAO as the catalytical system were [Ti]=1×10 -3 ?mol/L, T \-p=60℃,Al MAO /Ti=400(mol/mol) and Al TIBA /Ti=100.The oxidation states of active titanium centers in Cp\+*Ti(OBz) 3/MAO catalytic system have been determined by the redox titration method.It seems that the active center of Ti(Ⅲ) is favourable for butadiene polymerization with higher catalytic activity.